Is this for a solid state source or tube? Like you, I don't
have an permanent long range goal but just keep experimenting.

The TLAH sounds like a Voigt pipe with an array on
the baffle instead of one or two drivers. Where is
is the terminus of the horn?

I am not using any design programs yet and am fiddling
by ear. The big test for meis organ recitals rather than
cannon explosions. And I've been trying to ecerything with
length rather than more driver hardware. One of my listeners
liked a PVC tube arrangement I put together purely as an
experiment: one PVC tube the height of the listening room
which about 10 ft. The driver was way up near the ceiling
and the terminus down near the floor and both on PVC elbows.

It did sound pretty good for those low notes but I
couldn't live with it. I chopped it down and have some
bends with less length.

But this put me on another idea: PVC is real flexible.
I could have 2 drivers on elbows (sort of looking like
a letter "F") but I don't know how that would give the
ability to shorten length and maintain the the low
rumbles.

I will get to wood someday. :-)